You can kick the can down the road, but when Kim Jong Un announces, as he did last Sunday, that "we have reached the final stage in preparations to test-launch an intercontinental ballistic rocket," you are reaching the end of that road.

Since the early 1990s, we have offered every kind of inducement to get North Korea to give up its nuclear program. All failed miserably. Pyongyang managed to extort money, food, oil and commercial nuclear reactors in exchange. But it was all a swindle. North Korea was never going to give up its nukes because it sees them as the ultimate guarantee of regime survival.

The North Koreans believe that nukes confer inviolability. Saddam Hussein was invaded and deposed before he could acquire them. Kim won't let that happen to him. That's why Thae Yong Ho, a recent high-level defector, insisted that "As long as Kim Jong Un is in power, North Korea will never give up its nuclear weapons, even if it's offered $1 trillion or $10 trillion in rewards."

Meanwhile, they have advanced. They've already exploded a handful of nuclear bombs. And they've twice successfully launched satellites, which means they have the ICBM essentials. If they can miniaturize their weapons to fit on top of the rocket and control reentry, they'll be able to push a button in Pyongyang and wipe out an American city.

What to do? The options are stark:

(1) Preemptive attack on its missile launching facilities. Doable but reckless. It is the option most likely to trigger an actual war. The North Koreans enjoy both conventional superiority and proximity: a vast army poised at the Demilitarized Zone only 30 miles from Seoul. Americans are not going to fight another land war in Asia.

(2) Shoot down the test ICBM, as advocated by the Wall Street Journal. Assuming we can. Democrats have done their best to abort or slow down anti-missile defenses since Ronald Reagan proposed them in the early 1980s. Even so, we should be able to intercept a single, relatively primitive ICBM of the sort North Korea might be capable of.

Though such a shoot-down would occur nowhere near North Korean soil, it could still very well provoke a military response. Which is why the new administration should issue a clear warning that if such a test missile is launched, we will bring it down. Barack Obama is gone. Such a red line could be a powerful deterrent.

(3) Return tactical U.S. nuclear weapons to South Korea. They were withdrawn in 1991 by George H.W. Bush in the waning days of the Cold War. Gorbachev's Soviet Union responded in kind. A good idea in general, but not on the Korean Peninsula. Pyongyang had railed constantly against their presence, but they did act as a deterrent to any contemplated North Korean aggression. Which might make them a useful bargaining chip.

(4) Economic leverage on China, upon which Pyongyang depends for its survival. Donald Trump seems to suggest using trade to pressure China to get North Korea to desist. The problem is that China has shown no evidence of being willing to yield a priceless strategic asset - a wholly dependent client state that acts as a permanent thorn and distraction to U.S. power in the Pacific Rim - because of mere economic pressure.

(5) Strategic leverage on China. We've been begging China for decades to halt the North Korean nuclear program. Beijing plays along with sanctions and offers occasional expressions of dismay. Nothing more. There's one way guaranteed to get its attention. Declare that we would no longer oppose Japan acquiring a nuclear deterrent.

This is a radical step that goes against our general policy of nonproliferation. But the point is to halt proliferation to the infinitely more dangerous regime in North Korea. China is the key. The Chinese have many nightmares, none worse than a nuclear-armed Japan.

The principal strategic challenge facing the United States is the rise of revisionist powers - Russia, China and Iran - striving to expel American influence from their regions. In comparison, the Korean problem is minor, an idiosyncratic relic of the Cold War. North Korea should be a strategic afterthought, like Cuba. And it would be if not for its nukes.

That's a big if. A wholly unpredictable, highly erratic and often irrational regime is acquiring the capacity to destroy an American city by missile. That's an urgent problem.

North Korea may be just an unexploded ordnance of a long-concluded Cold War. But we cannot keep assuming it will never go off.